Saturday, December 25, 2010

California Rainfall Smashes Records By Wide Margin

The torrential rainfall of the past week set numerous records in California and the southwestern U.S. For the 7 days ending December 23, the precipitation totals were off the chart---over 600% of normal for at least half of California and Nevada, nearly all of Utah, most of Arizona, and eastward into southern Wyoming and western Colorado.

The National Weather Service has reported that the monthly totals so far are now the wettest on record for December at the airports in Los Angeles, Long Beach, Camarillo, Santa Barbara, and Santa Maria. In some of the higher elevations of interior southern California, storm totals ranged as high as 28". The printed amounts on the map to the right are a little hard to read, but note that the yellow areas represent 24-28", and the orange pixels are over 28".

Several daily rainfall records were broken by spectacular margins. In the San Joaquin Valley, at Bakersfield, California, the 1.37" on the 18th was over 4.5 times the previous record, which dated back to 1921. The 1.53" on the next day was more than triple the old record and easily beat the all-time daily record for December of 1.02" on the 27th in 1936. Bakersfield climate records go back to 1889. The 24-hour total of 2.31" on the 18th-19th was double the old December record of 1.15" on December 3-4, 1914. It was also the 3rd highest all-time 24-hour amount at Bakersfield, just behind the 2.32" on January 24-25, 1999. The monthly total of 4.95" so far has exceeded by nearly 2" the old December record of 2.98" set in 1931. This is now within striking distance of the all-time wettest month for Bakersfield, 5.36" in February 1998.

At the higher elevations of central California, snowfall was measured not in feet, but in tens of feet. Here are some of the more amazing estimated amounts:

Over 1900 daily rainfall records have been set through December 24 in the U.S., nearly 50% more than the total low temperature and high temperature records combined. Of these, 262 were set in California alone, with 58 on the 19th, 44 on the 20th, and 40 on the 22nd.

Meanwhile, despite the excess earlier in the month, daily low temperature records are less than 100 ahead of the daily high temperature records for December. The year-to-date ratio of heat records to cold records remains well in favor of the heat records at 2.4 to 1.

Images (click to enlarge): California, Nevada, Utah, and Arizona 7-day precipitation percentage of normal ending 7 am EDT, December 23 from National Weather Service (NWS); Storm total precipitation for southern California, December 17-23, from NWS; Monthly total of daily low temperature, high temperature, and precipitation records through December 24, CapitalClimate chart from National Climatic Data Center records